Standing on the Great Plains of North Dakota feels like straddling two oceans. The one beneath your feet is made of endless, rolling prairie. The other, above you, is clouds. When it rains, there are no trees to shield one world from the other. Prairie rain opens up the sky. It first falls as hard little droplets and then big, unyielding sobs.

It's raining the morning I try to find activist Lee Ann Eastman. Most people have abandoned the area around the main cook campfire to seek shelter from the dark clouds gathering overhead. And they're right to do so; in a matter of minutes, the water pounding the earth picks up into a deafening storm and turns the campground into mud.

I don't wait in the rain for long. A tribal councilman calls Lee Ann's name over the camp microphone, and a smiling young woman in a purple poncho comes running toward me from the parking lot. She motions for me to follow her, and together we dart toward her Yukon truck.

She hops in the driver's seat, and I close the passenger-side door with relief. Fat raindrops noisily pelt the car. A quick look around Lee Ann's truck shows it's been used for other kinds of rescues, too: The back seats are filled with dry logs for firewood, the trunk is full of extra clothing, and the console in front of the driver's armrest holds a bag of rice to dry out sodden cell phones.

Lee Ann's been here for more than three weeks after dropping in for what she thought was just going to be a weekend. She's from Sisseton, South Dakota, a 2,500-person town 260 miles from here where, up until three weeks ago, girls dressed up like Native "princesses" for the annual high school homecoming dance and had a fake "medicine man" predict who would become homecoming "chief." Student activists, including Lee Ann's niece, recently succeeded in changing the homecoming ceremony, but the Sisseton High School football team is still called the Sisseton Redmen.

That's only some of the casual racism that Lee Ann grew up around. But something changed for her, she says, when she watched an online video of a North Dakota police officer chasing and knocking down an elder walking in a field where Dakota Access pipeline builders bulldozed a sacred site in August.

"When I saw that video of the elder getting knocked down, when I saw the cries from the elders saying, 'Come here, please, we need you...' In our way of life, when you're asked for help like that, you can't turn away," Lee Ann says, her eyes fixed on the rain on her windshield. "I just knew that I had to do this right now."

Lee Ann doesn't share this with everyone she meets here at camp, but six months ago, she lost her mother. Della Eastman was an American Indian Movement activist who once took baby Lee Ann to her organizing meetings, and after she passed away in March, Lee Ann hit the summer powwow trail, searching for something that would give her a connection to home. It was on that powwow trail that she saw the video and made the split-second decision to come to camp, not even taking the time to pack properly.

Behind me, the truck door slams. A tall, lanky young man in thick glasses slides wordlessly into the backseat and pushes his smartphone cable toward the truck's charging outlet. Like Lee Ann, Layha Spoonhunter, 26, came here from Wyoming for a weekend that turned into three weeks. Layha, a motivational speaker, youth organizer, and Two Spirit advocate, has met President Obama twice in his work supporting indigenous youth. "Hey," he says, shaking some water off his Pendleton jacket. "It's going crazy."

The week certainly felt like something was cracking open. National media had suddenly picked up on the Dakota Access pipeline story, even though the Standing Rock Sioux Tribe had been organizing against the pipeline builders since April. Television crews from all over the country were dropping in for a day or two to interview tribal leaders—as were reporters from the BBC, the Washington Post, and, for whatever it's worth, Vice. Just days prior, Democracy Now!'s Amy Goodman, one of the only early reporters on the ground in North Dakota, captured the pipeline's privately hired security unleashing attack dogs on protesters—an act of journalism that both grabbed the attention of the wider world and resulted in criminal trespassing charges from the North Dakota authorities. With that, the camp, which had already tipped into the thousands, grew even bigger, and a new wave of small, direct action protests unsanctioned by tribal leadership captivated Twitter and Facebook: scenes of young, indigenous people locking themselves to construction equipment, surrounded by masked friends holding up their fists. That week, Green Party presidential candidate Jill Stein even showed up to one of these actions, spray-painting her own message on one of the bulldozers and expressing solidarity with a movement it wasn't clear she fully understood.

Behind the scenes, tension had been increasing between, on one side, prayerful elders who thought these actions read as aggressive and, on the other, action-seeking youth newly energized by a righteous sense of purpose. At the climax of this tension, in the days before a federal judge ruled to let the pipeline builders continue their work on the tribe's ancestral land, it would come to seem that the whole world had suddenly decided to tune in to the Standing Rock struggle. The whole world including the Obama administration, too, which effectively stayed the judge's decision—for the moment—by bringing a halt to pipeline work on the Missouri River and the 20 miles of land surrounding the disputed site.

The unprecedented size of the Standing Rock demonstrations, the Obama administration's intervention, the presence of the National Guard, the historic number of tribes coming together nonviolently—clearly something new was happening here on the plains, something that could have repercussions for any group of people, anywhere, fighting resource exploitation battles of the 21st century. But lost in the flurry of coverage explaining this historical moment was also something else: another, parallel movement unfolding, a movement that was obvious to spiritual leaders and to the thousands of people who had come to camp, a movement that is maybe impossible to describe to those who weren't there but is worth trying to somehow convey.

"When I walked down to Sacred Stone Camp, I got goose bumps," Lee Ann tells me as we sit in her Yukon. "I felt all of this emotion take over me. I can't even explain it."

She stares at the hundreds of tents and tepees and horse corrals in front of her that didn't exist a month ago, when she arrived. "I can feel it now coming over me," Lee Ann continues. "I just felt so empowered."

The last time people from all directions met like this, on ancestral land, was more than 140 years ago, at the Battle of the Greasy Grass (to many Americans, the Battle of Little Bighorn). On that day, a coalition of Lakota, Arapahoe, and Northern Cheyenne warriors came together to defeat Custer's 7th Cavalry, an arm of the US government attempting to exploit the Dakotas for gold mining.

Much has changed since then. Fourteen years later, the same regiment carried out a massacre of Lakota men, women, and children at Wounded Knee, in South Dakota. Nine years after that, white settlers demanded that the Great Sioux Reservation—a massive land base preserved by an 1868 treaty that covered the majority of South Dakota, much of North Dakota's Missouri River watershed, and connected to hunting grounds and unceded Native territory in Nebraska, Colorado, Wyoming, and Montana—be broken up into individual allotments and white homesteading. When federal commissioners couldn't secure the consent of most Lakota men (Lakota women didn't have the right to vote on such things, according to the 1868 Treaty of Fort Laramie), the Lakota and Dakota people at Standing Rock organized political resistance. Tribal spokespeople went to state conventions and decried the idea. Nevertheless, threats from the federal government to seize the land by force eventually coerced half the votes from men at Standing Rock. In 1889, Congress passed the "Sioux Bill," splitting up the Sioux nation into six smaller reservations, including Standing Rock. The Lakota and Dakota people lost nine million acres of ancestral land that day.

Seventy years later, the Standing Rock Sioux lost even more land. In 1958, the Army Corps of Engineers condemned 56,000 acres of the Standing Rock reservation in order to dam the Missouri and create an artificial reservoir called Lake Oahe. The Feds pushed Standing Rock Sioux families off their land and flooded the banks of the Missouri River, and to this day the tribe maintains that the federal government did not obtain their consent. On top of that—less quantifiable than acres, but equally if not more destructive—was the stolen culture and religion; over the course of the 20th century, a federal boarding-school policy would take Native children from their families and force them into schools that would attempt to culturally cleanse and assimilate them. In recent years, the Canadian government—which modeled its residential school policy off of the United States—has declared this practice within its borders an act of "cultural genocide."

According to the Standing Rock Sioux Tribe, this sordid history is repeating itself with today's oil pipeline construction along—and, potentially, underneath—the sole source of drinking water for the tribe's 8,000 members. In its current lawsuit against the Army Corps of Engineers, filed in late July after the Corps issued its nationwide pipeline permit to the Dakota Access subsidiary of Houston-based Energy Transfer Partners, the Standing Rock Sioux Tribe alleges, again, that the Corps is using their ancestral land and sacred sites without their consent—this time by approving the pipeline permit. But the type of resistance to this alleged violation of treaty rights is very different from the past. An unprecedented number of tribes—280 at the current count—have traveled to North Dakota or officially endorsed the Standing Rock Sioux's nonviolent movement against the Dakota Access pipeline. In Indian country, that kind of consensus is practically unheard of.

"We've never come together in such a fashion to defend one issue," Manaja Unjinca Hill, a veterans service officer at the tribe's Department of Veterans Affairs, tells me one day at camp, located just off the reservation on Army Corps land, looking across the prairie as cars haul in supplies and donations. He's been coming down here at least once every day, sometimes camping out for multiple nights.

According to Manaja, that may be because the Sacred Stone Camp has become a kind of cultural shorthand for something that indigenous people have in common. Tribes, Manaja says, understand the importance of water in a way that Europeans don't. "That's in our culture, that's in our DNA," he says.

It's even in the language, Matt Remle, a Seattle-area Lakota activist and educator, explains. The Lakota word for water, mni, translates directly to "it gives me life," he says. Mni wiconi, the Lakota saying written on signs and tepees all over camp, translates to "water is life"—life as in the tree of life, the source that connects all of humanity, and animals, and plants, and the earth together.

In a number of ceremonies—ceremonies that are happening at camp, beyond the reach of TV cameras or press access—some Lakota people are fasting, without food or water, for days on end. "When we do this it reminds us how essential that water is," Remle says. "Your relationship with it changes because you understand how vital it is."

From this perspective, it's basic common sense that you shouldn't build a 1,172-mile pipeline under the drinking water sustaining 8,000 people living on the Standing Rock Sioux reservation and millions more downstream. This perspective isn't isolated to the Lakota and Dakota nations; indigenous peoples all over the country have been fighting on the front lines to protect natural resources considered sacred to them since the beginning of white colonialism. In the present, there are innumerable examples here in Washington State, too: the Swinomish Indian Tribal Community suing BNSF over crude oil shipments, the Lummi Nation halting the development of what would have been the largest coal export facility in North America, the Yakama Nation and allies opposing a Nestlé bottling plant in the Columbia River Gorge, and more.

But it hasn't been easy for traditional knowledge to survive multiple attempts at forced cultural assimilation from the US government and churches over the last century. Land grabs and structural oppression have fragmented indigenous communities and cultures. Manaja says that it was also difficult for him to come back and rejoin his community after serving in the military. "As a veteran, we kind of lose a sense of belonging because we went from our reservations, from being Native, to becoming soldiers," he says.

What's happening here at Standing Rock is at once a new sense of belonging, and also something very old. "I wonder if, back in the day when our people actually camped out all the time, if they got that same feeling every time they came home," Manaja says.

"When we come together like this, it's proving to ourselves," he says, "that who we are is still here and it's not going to go away."

In the weeks after the Obama administration's intervention, the news cycle moved on from showing images of protesters standing on spray-painted bulldozers and dogs attacking indigenous people whose fists were raised into the air. LaDonna Brave Bull Allard, the original founder of the Sacred Stone Camp, has appeared on Democracy Now! and Salon, and traveled to New York to continue her activism. And now, it seems, the focus has shifted to more formal halls of power—although the camp in North Dakota, even with most of the news crews gone, is still humming. On September 20, nearly 5,000 miles away, Standing Rock Sioux chairman David Archambault II asked the UN Human Rights Council in Geneva, Switzerland, to call upon the US government to stop all construction on the pipeline, which continues to take shape outside the narrow, 20-mile zone near Lake Oahe.

Litigation within the United States against the Army Corps of Engineers is ongoing, too. On September 16, a federal appeals court overturned the lower court's ruling that allowed ongoing pipeline construction; on October 5, the first oral arguments will be heard on the tribe's motion for an emergency halt to pipeline construction nationwide.

But back at camp, it's getting colder. As temperatures drop, the cheap tents used by thousands of people in the summer months won't suffice. And while the size of the camp continues to fluctuate, it remains larger than most cities in North Dakota. On the camp's Facebook page, organizers are still distributing sign-up sheets for medic and traditional healer volunteers, posting videos of statements in solidarity with Black Lives Matter, and publishing drone videos of the camp. On a video published on September 22, an organizer wrote: "Are we all ready for this coming winter? As you see we are all still here. We are all still strong. We are native [peoples] and winter is [our] home. Stay strong! Stay united!!"

An old Lakota prophecy tells of a black snake that traverses the land and brings destruction to the Lakota people. To the Standing Rock Sioux and their allies, the Dakota Access pipeline is the black snake prophecy come to life.

"When the black snake dives into the ground, that'll be what is the last of our resources," Chief Arvol Looking Horse, spiritual leader of the Lakota, Dakota, and Nakota peoples, tells me one day, after we meet through a chance encounter near the computer lab of the Prairie Knights hotel on the Standing Rock reservation. He spoke at Bill Clinton's presidential inauguration, has met President Obama, and regularly addresses the United Nations. "They're saying that it's just Standing Rock," Looking Horse says, "but we're talking about this globally, because people need to wake up and hear all indigenous people all over the world."

Looking Horse has long warned of climate change as part of the prophecy from White Buffalo Calf Woman, a holy woman in Lakota theology who taught the Lakota people their ceremonies and gave them their Sacred White Buffalo Calf Pipe Bundle—a sacred object that has been protected for 19 generations and is currently kept by Chief Arvol Looking Horse.

"Mother Earth has a fever," he says. "White Buffalo Calf Woman said that someday, the next day I return and stand upon the earth as a white buffalo calf, there are going to be great changes that will take place with the environment, earth changes and climate changes. That's what we are faced with globally."

Looking Horse, who has been leading ceremonies at camp since the very beginning of the resistance back in April, is not the only person to explain the growing movement here at Sacred Stone Camp to me in terms of prophecies come to life. Here on these plains, I'm told over and over again, by pretty much anyone I meet, that the past lives through the present, and the present exists in two worlds that overlap.

Lee Ann tells me she thinks about her mother, up there in the stars with the others who have passed away on Earth. "They're helping with their prayers up there," Lee Ann says. "They're helping even though they're not here anymore. So even though it looks like sometimes we're a thousand to 5,000 in camp, there's really like thousands and thousands more. This is really bigger than anybody sees."

And here at Sacred Stone Camp, young supporters of the growing movement feel they are living another prophecy, too. "Not only is this event historic, but it's something that our ancestors talked about," Layha Spoonhunter says. "Our elders told us stories when we were growing up that someday the Seventh Generation will come together as one, and we're seeing it happen right now."

Layha and Lee Ann's parents, like many people's parents and grandparents at camp, spoke of this seventh generation as a group of people of all colors who would unite in a sacred place and save the world. It's this prophecy—the youth, the seventh generation alive right now—that Lee Ann says her elders have been praying for this whole time.